JPH0997922A - Light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element having a p- and n-type electrodes at a semiconductor layer having a large light-emitting region. SOLUTION: A light-emitting element has a substrate, semiconductor layers 2 and 3 grown on the substrate, and a first electrode 4 of first conductivity type and a second electrode 6 of second conductivity type at the semiconductor layers. The electrode 6 surrounds at least a part of the periphery of the electrode 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device such as a light emitting diode.

[0002]

2. Description of the Related Art Recently, GaN, GaAlN, InGa
Light-emitting devices made of gallium nitride-based semiconductors such as N and InAlGaN have been actively researched and developed because they are capable of emitting intense blue light having a short wavelength.

However, in general, in a light emitting device made of such a gallium nitride-based semiconductor, an insulating substrate such as sapphire is used.

In the light emitting element using this insulating substrate, it is difficult to form a structure in which one electrode is provided on the back surface of this substrate, and the p-type side and the n-type side are located on the semiconductor layer side (same surface side). A structure equipped with electrodes is adopted.

A light emitting device having both electrodes on the semiconductor layer side is disclosed in, for example, JP-A-6-338632 (H01L).
33/00).

FIG. 4 is a schematic top view (semiconductor layer side) of a conventional light emitting diode, and FIG. 5 is a schematic sectional view taken along the alternate long and short dash line AA in FIG.

In FIGS. 4 and 5, 101 is a sapphire substrate, 102 is an n-type GaN layer, 103 is a p-type GaN layer, 1
04 is an n-type side electrode formed on the n-type GaN layer 102,
Reference numeral 105 denotes a translucent p formed on the p-type GaN layer 103.
A mold side electrode 106 is a bonding pad formed at a corner of the p-type side electrode 105.

In this light emitting diode, the p-type side electrode 105
Light is extracted from the side.

[0009]

However, in the above-mentioned light emitting diode, the n-type side electrode 104 has the n-type GaN layer 10.
Since it exists only in the two corners, the current does not flow uniformly throughout the n-type GaN layer 102.

As a result, in the conventional light emitting diode, the light emitting region is narrow, and there is a possibility that the element may deteriorate due to current concentration.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a light emitting device having a p-type side electrode and an n-type side electrode on the semiconductor layer side having a large light emitting region.

[0012]

A light emitting device of the present invention comprises a substrate, a plurality of semiconductor layers grown on the substrate, and a first electrode for the first conductivity type on the semiconductor layer side. And the second
In a light emitting device including a second electrode for the conductivity type side, the second electrode is provided so as to surround at least a part of the first electrode region.

In particular, the second electrode is located on the uppermost layer of the second conductivity type of the plurality of semiconductor layers, and the first electrode is one of the plurality of semiconductor layers located around the uppermost layer. It is characterized in that it is located on the semiconductor layer of the first conductivity type.
In addition, it is preferable that the first electrode region is substantially the entire region on the uppermost layer.

Further, the second electrode is characterized in that it surrounds approximately half or more of the first electrode region.

Further, the first electrode is made of a translucent metal electrode.

In particular, the first electrode is composed of a linear metal electrode.

Further, the first electrode is characterized in that it is set to a thickness having a light transmitting property.

In addition, the first electrode is wire-bonded at the corner thereof, and the second electrode is wire-bonded at substantially the center of the second electrode on a substantially diagonal line from the corner. It is characterized by

Further, it is characterized in that the second electrode is arranged in a shape such that it is equidistant from the bonding portion of the first electrode.

In particular, the second electrode is characterized in that it surrounds approximately half of the first electrode region.

[0021]

DETAILED DESCRIPTION OF THE INVENTION A light emitting diode according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are schematic top views (semiconductor layer side) of the light emitting diode,
FIG. 2 is a schematic cross-sectional view taken along one-dot chain line AA in FIG. 1.

1 and 2, an n-type GaN layer 2 having a layer thickness of 3 μm and a p-type GaN layer 3 having a layer thickness of 1 μm are laminated in this order on an insulating substrate 1 such as sapphire, and p The periphery of the mold layer 3 is removed by etching to expose the n-type layer 2.

A light-transmitting substantially square p-type side electrode (first electrode) 4 made of Ni and having a film thickness of 100 Å is formed on substantially the entire area of the p-type GaN layer (uppermost layer) 3. , A bonding pad 5 made of Au having a film thickness of 1 μm at its end
Are formed.

On the exposed surface of the n-type layer 2, an L-shaped portion (around the area around the electrode area of the substantially rectangular p-type side electrode 4 facing the bonding pad 5) is formed. A layer thickness of 1 μm, which is formed in one opposing side area portion 6a and has a bonding pad portion 6b substantially in the center thereof.
An n-type side electrode (second electrode) 6 made of Al is provided around.

Although not shown, the bonding pad 5 and the bonding pad portion 6b are not shown in Au.
Bonding wires made of, etc. are respectively bonded and electrically connected to a lead frame or the like.

The thickness of the p-type side electrode 4 is set so that the emitted light can be transmitted, so that the p-type side electrode 4 has a light-transmitting property with respect to the emitted light, and the p-type side electrode 4 side becomes the light extraction side.

The p-type side electrode 4 is formed over substantially the entire area of the p-type GaN layer 3 so that a current flows substantially uniformly on the p-type side, and the n-type side electrode 6 is also p-type. By forming an L shape so as to surround the area of the mold side electrode 4, the current is made to flow more uniformly on the n type side. As a result, the current flows in a large area and substantially uniformly in the element including the light emitting region (pn junction surface), so that the light emitting area is large and current concentration does not substantially occur.

Moreover, in this embodiment, since the bonding pad 5 and the bonding pad portion 6b are located at the corners on the diagonal of the element, the current flowing through the element becomes more uniform.

A light emitting diode according to another embodiment of the present invention will be described with reference to FIG. 3 which is a schematic top view (semiconductor layer side). Note that, except for the p-type side electrode, it is the same as in the above-mentioned embodiment, and therefore its explanation is omitted.

In FIG. 3, on the p-type GaN layer 3, a film composed of an electrode portion 13 in which a linear electrode portion extends radially from substantially the center and a bonding pad 5 integrally connected to one end portion thereof. A p-type side electrode (first electrode) 14 having an Au / Ni structure is formed by stacking a Ni film having a thickness of 0.1 μm and an Au film having a thickness of 0.7 μm in this order.

On the exposed surface of the n-type layer 2, the electrode region (in the dotted line in the figure) 15 of the substantially square p-type side electrode 14 is formed so that the bonding pad 5 is desired as in the above embodiment.
N-type side made of Al having a layer thickness of 1 μm, which is formed in an L-shaped portion (one side-side area portion around the area) 6a and has a bonding pad portion 6b in the approximate center thereof. The electrode 6 is provided around.

By forming the p-type side electrode 14 into a linear shape so that the emitted light can pass therethrough, it has a light-transmitting property with respect to the emitted light, and the p-type side electrode 14 side becomes the light extraction side.

Since the electrode region 15 of the p-type side electrode 14 is substantially the entire region on the p-type GaN layer 3, a current flows substantially uniformly on the p-type side and the n-type side electrode is formed. 6 is also L-shaped so as to surround the periphery of the electrode region 15 of the p-type side electrode 14, so that the current flows more evenly on the n-type side. As a result, the current flows in a large area and substantially uniformly in the element including the light emitting region (pn junction surface), so that the light emitting area is large and current concentration does not substantially occur.

Moreover, also in this embodiment, since the bonding pad 5 and the bonding pad portion 6b are located at the corners on the diagonal of the element, the current flowing through the element becomes more uniform.

In addition, in the present embodiment as well, as in the above-described embodiment, the n-type side electrode 6 is selected such that the n-type side electrode 6 has a substantially equal distance from the bonding pad 5 of the p-type side electrode 14, so that it is further selected. The current is made uniform.

It should be noted that the n-type electrode is effective even if the n-type electrode is provided to be less than approximately half of the p-type side electrode region. It is preferable that the above can be made uniform, and it is also possible to provide substantially the entire circumference.

In the above description, the n-type layer and the p-type layer are formed in this order on the substrate. However, the p-type layer and the n-type layer may be formed in this order on the substrate. The configurations on the mold side and the n-type side are opposite to the above.

Of course, the light emitting diode having a single pn junction has been described above, but a double hetero structure or a double hetero structure including an active layer having a quantum well structure may be used.

The present invention is not limited to light emitting diodes,
It is also applicable to surface-emitting lasers and the like.

[0040]

The light emitting device of the present invention comprises a substrate, a plurality of semiconductor layers grown on the substrate, and the first conductive type first electrode and the second conductive type on the semiconductor layer side. In the light emitting device including the second electrode for the mold side, since the second electrode surrounds at least a part of the first electrode region, the current flowing through the device has a large area. And it becomes more uniform.

As a result, the light emitting area is large and the device life is long.

The second electrode is located on the uppermost layer of the second conductivity type of the plurality of semiconductor layers, and the first electrode is among the plurality of semiconductor layers located around the uppermost layer. When it is located on the semiconductor layer of the first conductivity type, it is easy to increase the light emitting area, and wire bonding can be performed on the same surface side, which simplifies the bonding.

Further, when the second electrode surrounds approximately half or more of the first electrode region, the current flowing in the element becomes large in area and uniform.

In addition, the first electrode is wire-bonded at the corner thereof, and the second electrode is wire-bonded at substantially the center of the second electrode on a diagonal line substantially diagonal to the corner. In this case, since the distance between the current input / output ports becomes large, the current flowing through the element becomes even larger in area and uniform.

Further, when the second electrode is arranged in a shape such that it is equidistant from the bonding portion of the first electrode,
The flow of current can be remarkably made uniform.

Particularly, good effects can be obtained even if the second electrode is provided so as to surround approximately half of the first electrode region.

[Brief description of drawings]

FIG. 1 is a schematic top view of a light emitting diode according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a light emitting diode according to the above embodiment.

FIG. 3 is a schematic top view of a light emitting diode according to another embodiment of the present invention.

FIG. 4 is a schematic top view of a conventional light emitting diode.

FIG. 5 is a schematic sectional view of the conventional light emitting diode.

[Explanation of symbols]

 1 substrate 2 n-type layer 3 p-type layer 6 n-type side electrode 4, 14 p-type side electrode 15 p-type side electrode region

Claims (9)

[Claims] 1. A substrate, a plurality of semiconductor layers grown on the substrate, and a first electrode for the first conductivity type side and a second conductivity type side on the same surface side that is the semiconductor layer side. And a second electrode for use in the light emitting element, wherein the second electrode surrounds at least a part of the first electrode region. 2. The second electrode is located on the uppermost layer of the second conductivity type among the plurality of semiconductor layers, and the first electrode of the plurality of semiconductor layers located around the uppermost layer. The light emitting device according to claim 1, wherein the light emitting device is located on the first conductive type semiconductor layer. 3. The method according to claim 1, wherein the second electrode is provided so as to surround substantially the half of the first electrode region.
The light-emitting element according to any one of the preceding claims. 4. The light emitting device according to claim 1, wherein the first electrode is a translucent metal electrode. 5. The light emitting device according to claim 4, wherein the first electrode is a linear metal electrode. 6. The light emitting device according to claim 4, wherein the first electrode is set to have a light transmitting property. 7. The first electrode is wire-bonded at a corner thereof, and the second electrode is wire-bonded at a substantially center of the second electrode on a substantially diagonal line from the corner. Claims 1, 2, 3, 4,
5. The light emitting device according to 5 or 6. 8. The configuration according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the second electrode is arranged in a shape that is equidistant from the bonding portion of the first electrode. Light emitting element 9. The method according to claim 1, wherein the second electrode surrounds substantially half of the first electrode region.
The light emitting device according to 4, 5, 6, 7, or 8.